One way to restrict access to online content or services is to use username/password authentication. Username/password authentication is easily thwarted, however, when unauthorized users are told or otherwise obtain the username/password of authorized users.
In some online environments, such as online education, it is particularly important to ensure that the person using log-in credentials is the actual person that was provided those log-in credentials. For example, the integrity of tests that are administered online would be compromised if one student takes the test under another student's log-in credentials. Therefore, a need exists for an additional method of authentication that helps ensure that the person using an online service is the person that the online service believes is using the online service.